The invention relates to the vulcanization of rubber hose utilizing a vulcanizing fluid to transport and vulcanize a hose with means for recirculating the vulcanizing fluid.
Present techniques for the manufacture of rubber hose includes forming an unvulcanized elastomeric hose structure around a flexible, solid rubber mandrel, encasing the hose and mandrel within a pressure sheath or suitable cover and thence vulcanize the hose. The sheath is considered necessary to maintain pressure against the hose's outer surface preventing any defects which might otherwise develop during vulcanization. For vulcanization, the supported lengths of sheathed, mandreled, unvulcanized hose are then placed in heated enclosures, such as ovens, where they remain until cured. After removal from the oven, the outer sheath is stripped and the internal mandrel removed from the vulcanized hose.
Modifications on this technique include improved hose vulcanization by obviating need for the normally necessary outer pressure sheath and/or effecting vulcanization or cure of hose in a more continuous manner. One improvement in the continuous method passed the sheathed hose into a vulcanizing chamber, around a moving spool and withdrawal from the chamber thereafter. Another technique passed the hose through a tubular chamber by means of hot vulcanizing fluid such as oil.
Principal advantages allegedly achieved by transport of hose through a tubular chamber by hot fluid are that the use of an outer pressure sheath over the hose during cure is unnecessary, and reduces the area necessary to manufacture the hose. However, the tubular chamber with the hot vulcanizing fluids does have its drawbacks in requiring higher pressures on the fluids while transporting the hose. In addition, pressurization of the curing and transporting fluid is essential to maintain the inner diameter of the hose.
Additional problems of safety has limited its widespread use since the fluids are hot and turbulence and splashing within the fluid recovery system entrains air and accelerates oxidation degradation of the hot vulcanizing fluids. Special seals have helped in reducing the splashing of the hot fluids.